
are the trace of the right Cauchy-Green deformation tensor and its square, respectively.
The nonlinear strain energy density of the Mooney–Rivlin model is given by [1]}, [2]}
\(U=\left[ \frac{\mu _1}{2} \left(I- 3\right) + \frac{\mu _2}{2} \left(K- 3\right) + \frac{\kappa }{2} \left(J-1\right)^2\right] \:,\) 
